Page 598 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

THEhumanDENOMINATOR 17 Glaciers and Permafrost
GLACIAL ENVIRONMENTS HUMANS
• Glacial ice is a freshwater resource; ice masses affect sea level, which is linked to the security of human population centres along coastlines. • Snow avalanches are a significant natural hazard in mountain environments.
• Permafrost soils are a carbon sink, estimated to contain half the pool
HUMANS GLACIAL ENVIRONMENTS
• Rising temperatures associated with human-caused climate change are accelerating ice sheet losses and glacial melting, and hastening permafrost thaw.
• Particulates in the air from natural and human sources darken snow and ice surfaces, which accelerates melting.
of global carbon.
17a
A USGS scientist photographs Grinnell Glacier in Glacier National Park, Montana, as part of a repeat photography project to document the effects of climate change on glacial retreat. [USGS/Lisa McKeon, Northern Rocky Mountain Science Center.]
17c
Greenland Melt Extent 2012 and 2013
2013 melt percentage
2012 melt percentage 1981–2010 average
The northern ice field in the summit crater of Mount Kilimanjaro, Africa’s highest mountain, has shrunk in size with dry season melting, and broke into two sections in 2012. Note expedition tents at the base of the ice, and automated meteorological stations on top. Scientists attribute the disappearing glaciers to climate change as well as other factors, such as a drier atmosphere that is depriving the glacier of snowfall to sustain the ice fields. Glacial research is ongoing at the 5803-m summit. [Photo by
Dr. Kimberly Casey.]
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17b
In the Indian-controlled region of Kashmir, avalanches buried a military camp and killed 16 Indian soldiers in February 2012. Three months later, 100 Pakistani soldiers were killed nearby in another avalanche. This area receives a large volume of snowfall and frequent winds, which combine with steep Himalayan slopes to create dangerous avalanche conditions. [Dar Yasin.]
Surface melt on the Greenland Ice Sheet in 2012 reached its greatest extent in the satellite record since 1979. Melt during 2013 was closer to average (dotted line). [Courtesy National Snow and Ice Data Center/Thomas Mote, University of Georgia.]
ISSUES FOR THE 21ST CENTURY
• Melting of glaciers and ice sheets will continue to raise sea level, with potentially devastating consequences for coastal communities and low-lying island nations.
• Thawing of permafrost in response to climate change will release vast amounts of carbon into the atmosphere, accelerating global warming.
geosystemsconnection
Our look at the cryosphere and glacial and periglacial processes and landforms ends Part III, “The Earth–Atmosphere Interface.” We examined past and present alpine and continental glaciations and the ways in which Earth’s landscapes bear the mark of past glacial phases. The polar regions are undergoing rapid change at a pace faster than the lower latitudes. We shift now to Part IV, “Soils, Ecosystems, and Biomes.” A synthesis of Parts I through III, these next three chapters focus on the biosphere and the subdiscipline of biogeography.
Daily % Showing Surface Melt
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